Theres the Photon 4G and the Photon Q (QWERTY phone) I know it has the ability to unlock the boot loader, but i'd also say don't get it as its pretty outdated at this point in time. Maybe aim for a nexus 5. I'd recommend the Note 2 or 3 as they can be customized. The note 2 shouldn't be too expensive now and still an awesome phone they both also have expandable memory. It also looks like you can get a deal on sprint's website on the note 2.
You should be very carefull with rooting your phones. though it gives you more access to the system it could also open your phone to security risks since security measures may be removed in the process